I had the same issue. I have ordered ethernet over powerline (XAVB5004 kit), which gives a powerline adapter for one end, and essentially a 4-port powerline router for the other. It has arrived, but I haven't tested it yet.

Most reviews are fairly clear that throughput and stability on this should greatly exceed WiFi. My plan is to connect most devices (2x media players, NAS, Tivo and main router etc) this way, ultimately using 2 kits if it works, and with Wifi only being used for untethered devices.

It's a fairly cheap solution, and if most of your devices are stationary it might be exploring this as an option instead of WiFi?

Zeon: Probably best to run multiple access points on different channels. You could get the triple pack Ubiquiti Unifi?

With out knowing anything about the site at all, I agree with the general direction you're suggesting.

The OP should also do a site servey and see just how much other junk is in the air. I had a customer complain on Friday and I just showed them the noise on my phone and they got it fast enough.

The power line suggestion is a good one for fixed devices if you can't just run some CAT5 to them.

A Unifi triple pack will also need a controller in a space that small so the radios know about each other and don't just make the problem worse.

Fixing APs on fixed channels isn't ideal. If a neighbour jumps a radio in on one of your channel selections then the problem just comes back. The Unifi network will sort that out for you automatically and move the radios about as required.

Interesting to see what sort of value people out on wifi moving forward. People think nothing of paying $3,000 for a TV. Wonder how many people will be happy to pay $1,000 for a half decent Unifi set up?